Degradation of oil products in a soil from a Russian Barents hot-spot during electrodialytic remediation.

Kristine B Pedersen,Pernille E Jensen,Tore Lejon,Lisbeth M Ottosen

doi:10.1186/s40064-016-1882-5

Kristine B Pedersen, Pernille E Jensen + Show 2 more

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https://doi.org/10.1186/s40064-016-1882-5

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Abstract

A highly oil-polluted soil from Krasnoe in North-West Russia was used to investigate the degradation of organic pollutants during electrodialytic remediation. Removal efficiencies were up to 70 % for total hydrocarbons (THC) and up to 65 % for polyaromatic hydrocarbons (PAH). Relatively more of the lighter PAH compounds and THC fractions were degraded. A principal component analysis (PCA) revealed a difference in the distribution of PAH compounds after the remediation. The observed clustering of experiments in the PCA scores plot was assessed to be related to the stirring rate. Multivariate analysis of the experimental settings and final concentrations in the 12 experiments revealed that the stirring rate of the soil suspension was by far the most important parameter for the remediation for both THC and PAH. Light was the second most important variable for PAH and seems to influence degradation. The experimental variables current density and remediation time did not significantly influence the degradation of the organic pollutants. Despite current density not influencing the remediation, there is potential for degrading organic pollutants during electrodialytic removal of heavy metals, as long as a stirred set-up is applied. Depending on remediation objectives, further optimisation may be needed in order to develop efficient remediation strategies.

Highlights

Electrodialytic remediation (EDR) is a technology viable for removing heavy metals from polluted soil (Ottosen et al 1997); the effect on organic pollutants has yet to be investigated
EDR is based on the principles of electrokinetic remediation (EKR) in which an electric field is applied directly to the soil and electrolysis reactions at the inert electrodes produces protons at the anode and hydroxyl ions at the cathode (Acar and Alshawabkeh 1993)
Transport of nutrients and electron donors/acceptors is dominated by electromigration, while the transport of hydrophobic contaminants is dominated by electroosmosis (Gill et al 2014; Lohner et al 2009; Wick 2009)

Summary

Introduction

Electrodialytic remediation (EDR) is a technology viable for removing heavy metals from polluted soil (Ottosen et al 1997); the effect on organic pollutants has yet to be investigated. EDR is based on the principles of electrokinetic remediation (EKR) in which an electric field is applied directly to the soil and electrolysis reactions at the inert electrodes produces protons at the anode and hydroxyl ions at the cathode (Acar and Alshawabkeh 1993). The coupling of EKR with bioremediation has been shown to increase removal efficiencies of hydrophobic organic contaminants such as polyaromatic hydrocarbons (PAH) and total petroleum hydrocarbons (TPH) in soil/sediments (Dong et al 2013; Gill et al 2014; Kim et al 2010; Li et al 2012; Lohner et al 2009; NiquiArroyo et al 2006; Wang et al 2013; Wick 2009). The bioavailability of hydrophobic contaminants is increased by advancing contact between the catabolically active microorganisms, nutrients, electron donors/acceptors and contaminants. Transport of nutrients and electron donors/acceptors is dominated by electromigration, while the transport of hydrophobic contaminants is dominated by electroosmosis (Gill et al 2014; Lohner et al 2009; Wick 2009). The electrolysis reactions (Fig. 1) may be used to increase degradation adjacent to the electrodes, in which H2 acts as electron donors and O2 acts as electron acceptors (Lohner et al 2009)

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